Poly-gamma-glutamic acid (PGA) is a viscous polymer consisting of D and L-glutamic acids polymerized through gamma-glutamyl bonds. It is produced from Bacillus sp. strains isolated from Chungkookjang (Korean traditional fermented soybean food prepared using rice-straw), Natto (Japanese traditional fermented soybean food), Kinema (Nepalese traditional fermented soybean food), etc. PGA that is produced from Bacillus sp. strains is an edible, water-soluble, anionic, and biodegradable polymeric substance. It is known that the PGA can be used as a raw material for moisture absorbers, moisturizers and cosmetics, and as a raw material for the preparation of naturally degradable plastics by using the synthesis of ester derivatives.
The present inventors have obtained a patent (Korean Patent No. 10-500796) directed to a method of producing poly-gamma-glutamic acid using a Bacillus subtilis Chungkookjang strain that is a salt-tolerant strain producing high-molecular-weight poly-gamma-glutamic acid. Also, the present inventors have obtained patents (Korean Patent Nos. 10-496606, 10-517114 and 10-475406) directed to an anticancer composition, an immune adjuvant and an immune enhancer, which contain poly-gamma-glutamic acid (PGA). In recent years, a patent directed to an anticoagulant and antithrombotic composition containing poly-gamma-glutamic acid has been granted (Korean Patent No. 10-0656560).
An immune adjuvant or enhancer containing poly-gamma-glutamic acid has been used together with an antibody for the purpose of increasing antibody immunity. In this regard, poly-gamma-glutamic acid alone did not serve to increase immunity.
Meanwhile, cervical neoplasia is the beginning stage of cervical cancer in which cervical epithelial cells are transformed into dysplastic cells by infection with human papillomavirus. As gynaecological examination has been widely conducted, cervical neoplasia, which is the beginning stage of cervical cancer, has recently been diagnosed, but appropriate treatment of cervical neoplasia with drugs has not been performed. Cervical neoplasia is divided into three stages in accordance with the type of symptoms. In the case of stage 1 cervical neoplasia, it is the best choice to watch the progress of the disease. However, if stage 2 or stage 3 cervical neoplasia is diagnosed, surgery should be taken into consideration together with diagnosis, because a further advanced lesion may exist.
Particularly, if cervical neoplasia is diagnosed as stage 3, a lesion more severe than stage 3 may exist, and thus surgical procedures such as cervical conization may be performed. Cervical conization is a medical procedure in which a cone-shaped tissue is excised from the cervix. Since an infected site is removed, it appears that guaranteed removal of HPV virus is possible; however, cervical neoplasia is often unexpectedly recurred. Because cervical conization in unmarried women, pre-childbirth women, or women who do not want infertility, can cause sequelae such as abortion, premature birth, difficult pregnancy or infertility, immunotherapy with drugs is preferable.
Accordingly, the present inventors have made extensive efforts to develop a method capable of treating cervical intraepithelial neoplasia without surgery, and as a result, have found that, when a composition containing poly-gamma-glutamic acid is administered to a patient with cervical intraepithelial neoplasia, it causes no side effects and exhibits a high therapeutic effect with high stability, thereby completing the present invention.